Lead, other chemicals taint some urban gardens

In this photo taken Dec. 3, 2010, Tim Beckman looks away as one of his four chickens takes flight as he holds it in the backyard of his Indianapolis home. Beckman raises the chickens for the dozen or so eggs they produce a week. He also has several garden plots in his urban yard and had had the soil tested for possible lead contamination. (AP Photo/Michael Conroy)
— AP

In this photo taken Dec. 3, 2010, Tim Beckman looks away as one of his four chickens takes flight as he holds it in the backyard of his Indianapolis home. Beckman raises the chickens for the dozen or so eggs they produce a week. He also has several garden plots in his urban yard and had had the soil tested for possible lead contamination. (AP Photo/Michael Conroy)
/ AP

While no one knows exactly how many urban residents are growing food, the U.S. Department of Agriculture estimates there are thousands of community gardens nationwide. The American Community Gardening Association said it has more than 2,600 active listings in its online database and has seen a steady increase in people inquiring about community gardening in recent years.

In the Boston suburbs of Roxbury and Dorchester, where four out of five backyard gardens tested had high lead levels, new research has suggested that a one-time fix isn't enough to keep soil safe. The nonprofit Food Project installed raised beds filled with freshly composted soil, but tests showed the lead content in some tripled in just four years. Researchers say that while more study is needed, the early results suggest growers need to change the way they think about city soil and test not only when they first plant but as years go by.

"It's not a static situation," said one of the researchers, Daniel Brabander, an associate professor at Wellesley College. "It's very prudent to characterize it at the start, but depending on neighborhood where you're doing this, it is evolving."

The Food Project has recommended growers also take simple yet potentially effective steps to reduce exposure to contaminated soil by washing their hands after gardening, washing vegetables thoroughly and trying not to track soil indoors.

Murray McBride, director of Cornell Waste Management Institute, said its analysis of garden beds in New York City generally has been encouraging, with one pilot study of 44 gardens finding less than 10 percent had high lead levels in the soil. He said efforts there to bring in clean soil and compost for raised beds may be why lead was less of a problem.

A lack of standard practices as urban agriculture expands has made the problem difficult to assess. Dave Weatherspoon, an associate professor at Michigan State University who studies food issues in Detroit, where urban farming is taking off, said more research is needed to provide a better understanding of what soil contamination could mean for crops and what should be done about it.

"We don't want people to feel that their food isn't safe," Weatherspoon said. "That is the worst thing that can happen to the U.S. food system."